Method of producing plasma display panel with protective layer of an alkaline earth oxide

ABSTRACT

The first object of the present invention is to provide a PDP with improved panel brightness which is achieved by improving the efficiency in conversion from discharge energy to visible rays. The second object of the present invention is to provide a PDP with improved panel life which is achieved by improving the protecting layer protecting the dielectrics glass layer. To achieve the first object, the present invention sets the amount of xenon in the discharge gas to the range of 10% by volume to less than 100% by volume, and sets the charging pressure for the discharge gas to the range of 500 to 760 Torr which is higher than conventional charging pressures. With such construction, the panel brightness increases. Also, to achieve the second object, the present invention has, on the surface of the dielectric glass layer, a protecting layer consisting of an alkaline earth oxide with (100)-face or (110)-face orientation. The protecting layer, which may be formed by using thermal Chemical Vapor Deposition (CVD) method, plasma enhanced CVD method, or a vapor deposition method with irradiation of ion or electron beam, will have a high sputtering resistance and effectively protect the dielectrics glass layer. Such a protecting layer contributes to the improvement of the panel life.

This application is a reissue of U.S. Pat. No. 5,993,543, applicationSer. No. 08/890,577 filed on Jul. 10, 1997.

This is a divisional application of Ser. No. 08/766,030, filed on Dec.16, 1996, now issued as U.S. Pat. No. 5,770,921.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to a plasma display panel used as a displaydevice and the method of producing the display panel, specifically to aplasma display panel suitable for a high-quality display.

(2) Description of the Prior Art

Recently, as the demand for high-quality large-screen TVs such ashigh-vision TVs have increased, displays suitable for such TVs, such asCathode Ray Tube (CRT), Liquid Crystal Display (LCD), and Plasma DisplayPanel (PDP), have been developed.

CRTs have been widely used as TV displays and excel in resolution andpicture quality. However, the depth and weight increase as the screensize increases. Therefore, CRTs are not suitable for large screen sizesexceeding 40 inch. LCDs consume a small amount of electricity andoperate on a low voltage. However, producing a large LCD screen istechnically difficult, and the viewing angles of LCDs are limited.

On the other hand, it is possible to make a PDP with a large screen witha short depth, and 40-inch PDP products have already been developed.

PDPs are divided into two types: Direct Current (DC) and AlternatingCurrent (AC). Currently, PDPs are mainly AC-type since they are suitablefor large screens.

FIG. 1 is a sectional view of a conventional AC PDP. In the drawing,front cover plate 1, with display electrodes 2 put thereon, is coveredby dielectric glass layer 3 which is lead glass, namely, PbO-B₂O₃-SiO₂glass.

Set on back plate 5 are address electrode 6, partition walls 7, andfluorescent substance layer 8 consisting of red, green, or blueultraviolet excited fluorescent substance. Discharge gas is charged indischarge space 9 which is sealed with dielectrics glass layer 3, backplate 5, and partition walls 7.

The discharge gas is generally helium (He), xenon (Xe), or mixture ofneon (Ne) and Xe. The amount of Xe is generally set to a range from 0.1to 5% by volume, preventing the drive voltage of the circuit frombecoming too high.

Also, the charging pressure of the discharge gas is generally set to arange from 100 to 500 Torr so that the discharge voltage is stable(e.x., M. Nobrio, T. Yoshioka, Y. Sano, K. Nunomura, SID94' Digest, pp.727-730, 1994).

PDPs have the following problems concerning brightness and life.

Currently, PDPs for 40-42-inch TV screens generally have a brightness ofabout 150-250 cd/m² for National Television System Committee (NTSC)standard (number of pixels being 640×480, cell pitch 0.43 mm×1.29 mm,square of one cell 0.55 mm²) (Function & Materials, Feb., 1996, Vol. 16,No. 2, page 7).

On the contrary, in 42-inch high-vision TVs, number of pixels is1,920×1,125, cell pitch 0.15 mm×0.48 mm, and square of one cell 0.072mm². This square of one cell is 1/7-⅛ of that of NTSC standard.Therefore, it is expected that if PDP for 42-inch high-vision TV is madewith the conventional cell construction, the screen brightness decreasesto 30-40 cd/m².

Accordingly, to acquire, in a PDP used for a 42-inch high-vision TV, thesame brightness as that of a current NTSC CRT (500 cd/m²), thebrightness of each cell should be increased about 12-15 times.

In these circumstances, it is desired that the techniques for increasingthe brightness of PDP cells are developed.

The light-emission principle in PDP is basically the same as that influorescent light; a discharge lets the discharge gas emit ultravioletlight; the ultraviolet light excites fluorescent substances; and theexcited fluorescent substances emit red, green, and blue lights.However, since discharge energy is not effectively converted toultraviolet light and conversion ratio in fluorescent substance is low,it is difficult for PDPs to provide brightness as high as that offluorescent lights.

It is disclosed in Applied Physics, Vol. 51, No. 3, 1982, pp. 344-347 asfollows: in PDP with He-Xe or Ne-Xe gas, only about 2% of the electricenergy is used in ultraviolet light, and about 0.2% of the electricenergy is used in visible rays (Optical Techniques Contact, Vol. 34, No.1, 1996, page 25 and FLAT PANEL DISPLAY 96, Parts 5-3, NHK TechniquesStudy, 31-1, 1979, page 18).

Accordingly, to increase light-emission efficiency is considered asimportant in increasing the brightness of PDP cells.

Now, regarding to the PDP life, the following are generally consideredto determine the PDP life: (1) the fluorescent substance layerdeteriorates since plasma is confined to a small discharge space togenerate ultraviolet light; and (2) the dielectrics glass layerdeteriorates due to sputtering by gas discharges. As a result, methodsfor extending the fluorescent substance life or preventing thedeterioration of dielectric glass layer are studied.

As shown in FIG. 1, in conventional PDPs, protecting layer 4 consistingof magnesium oxide (MgO) is formed on the surface of dielectrics glasslayer 3 with a vacuum vapor deposition method to prevent the dielectricsglass layer from deteriorating.

It is desirable that protecting layer 4 has high sputtering resistanceand emits a large amount of secondary electrons. However, it isdifficult for a magnesium oxide layer formed by the vacuum vapordeposition method to obtain a protective layer having enough sputteringresistance. There is also a problem that discharges decrease the amountof secondary electron emitted.

SUMMARY OF THE INVENTION

It is therefore the first object of the present invention to provide aPDP with improved panel brightness which is achieved by improving theefficiency in conversion from discharge energy to visible rays. It isthe second object of the present invention to provide a PDP withimproved panel life which is achieved by improving the protecting layerprotecting the dielectric glass layer.

To achieve the first object, the present invention sets the amount of Xein the discharge gas to the range of 10% by volume to less than 100% byvolume, and sets the charging pressure for the discharge gas to therange of 500 to 760 Torr which is higher than conventional chargingpressures. With such construction, the panel brightness increases. Theassumed reasons for it are as follows: the increase In the amount of Xein the discharge space increases the amount of ultraviolet lightemitted; the ratio of excitation wavelength (173 nm of wavelength) bymolecular beam of Xe molecules In the emitted ultraviolet lightincreases; and this increases the efficiency of a conversion fromfluorescent substance to visible rays.

Also, to achieve the second object, the present invention has, on thesurface of the dielectrics glass layer, a protecting layer consisting ofan alkaline earth oxide with (100)-face or (110)-face orientation.

The conventional protecting layer of magnesium oxide formed by vacuumvapor deposition method (electron-beam evaporation method) has(111)-crystal-face orientation. Compared to this, the protecting layerof an alkaline earth oxide with (100)-face or (110)-face orientation isdense, has high sputtering resistance, and emits a great amount ofsecondary electrons.

Accordingly, the present invention prevents deterioration of thedielectric glass layer and keeps the discharge voltage low.

Also, such effects are further improved by using thermal Chemical VaporDeposition (CVD) method or plasma enhanced CVD method, both of whichhave not been used as methods of forming protecting layers, to form analkaline earth oxide with (100)-face orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings which illustrate a specificembodiment of the invention. In the drawings:

FIG. 1 is a sectional view of a conventional AC PDP;

FIG. 2 is a sectional view of an AC PDP described in an embodiment ofthe present invention;

FIG. 3 shows a CVD apparatus used for forming protecting layer 14;

FIG. 4 is a graph showing the relation between the wavelength and amountof the ultraviolet light for each charging pressure, the ultravioletlight being emitted from Xe in He-Xe gas used as a discharge gas in aPDP;

FIGS. 5(a)-(c) shows relation between excitation wavelength and relativeradiation efficiency for each color of fluorescent substance;

FIG. 6 is a graph showing relation between charging pressure P of thedischarge gas and discharge start voltage Vf for two values of distanced, d being a distance between dielectric electrodes in a PDP; and

FIG. 7 shows an ion/electron beam irradiating apparatus which is usedfor forming a protecting layer in the PDP of Embodiment 3.

Tables 1-4 processing conditions and PDP characteristics.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Structure andProduction Method

FIG. 2 is a sectional view of a discharge PDP of the present embodiment.Though FIG. 2 shows only one cell, a PDP includes a number of cells eachof which emits red, green, or blue light.

The present PDP includes: a front panel which is made up of front glasssubstrate 11 with display electrodes 12 and dielectric glass layer 13thereon; and a back panel which is made up of back glass substrate 15with address electrode 16, partition walls 17, and fluorescent substancelayer 18, the front panel and back panel being bonded together.Discharge space 19, which is sealed with the front panel and back panel,is charged with a discharge gas. The present PDP is made as follows.

Producing the Front Panel

The front panel is made by forming display electrodes 12 onto frontglass substrate 11, covering it with dielectrics glass layer 13, thenforming protecting layer 14 on the surface of dielectric glass layer 13.

In the present embodiment, discharge electrodes 12 are silver electrodeswhich are formed by transferring a paste for the silver electrodes ontofront glass substrate 11 with screen printing then baking them.Dielectric glass layer 13, being lead glass, is composed of 75% byweight of lead oxide (PbO), 15% by weight of boron oxide (B₂O₃), and 10%by weight of silicon oxide (SiO₂). Dielectrics glass layer 13 is alsoformed with screen printing and baking.

Protecting layer 14 consists of an alkaline earth oxide with (100)-faceorientation and is dense. The present embodiment uses a CVD method(thermal CVD method or plasma enhanced CVD method) to form such a denseprotecting layer consisting of magnesium oxide with (100)-faceorientation. The formation of the protecting layer with the CVD methodwill be described later.

Producing the Back Panel

The back panel is made by transferring the paste for the silverelectrodes onto back glass substrate 15 by screen printing then bakingback glass substrate 15 to form address electrodes 16 and by attachingpartition walls 17 made of glass to back glass substrate 15 with acertain pitch. Fluorescent substance layer 18 is formed by inserting oneof a red fluorescent substance, a green fluorescent substance, a bluefluorescent substance into each space surrounded by partition walls 17.Any fluorescent substance generally used for PDPs can be used for eachcolor. The present embodiment uses the following fluorescent substances:

-   -   red fluorescent substance (Y_(x)Gd_(1-x))BO₃: Eu³⁺    -   green fluorescent substance BaAl₁₂O₁₉: Mn    -   blue fluorescent substance BaMgAl₁₄O₂₃: Eu²⁺

Producing a PDP by Bonding Panels

A PDP is made by bonding the above front panel and back panel withsealing glass, at the same time excluding the air from discharge space19 partitioned by partition walls 17 to high vacuum (8×10⁻⁷ Torr), thencharging a discharge gas with a certain composition into discharge space19 at a certain charging pressure.

In the present embodiment, cell pitch is under 0.2 mm and distancebetween electrodes “d” is under 0.1 mm, making the cell size of the PDPconform to 40-inch high-vision TVs.

The discharge gas is composed of He-Xe gas or Ne-Xe gas, both of whichhave been used conventionally. However, the amount of Xe is set to 10%by volume or more and the charging pressure to the range of 500 to 700Torr.

Forming the Protecting Layer with the CVD Method

FIG. 3 shows a CVD apparatus used for forming protecting layer 14.

For the CVD apparatus, either of the thermal CVD method and plasmaenhanced CVD method is applicable. CVD apparatus 25 includes heater 26for heating glass substrate 27 (equivalent to front glass substrate 11with display electrodes 12 and dielectric glass layer 13 as shown inFIG. 2). The pressure inside CVD apparatus 25 can be reduced by ventingapparatus 29. CVD apparatus 25 also includes high-frequency power 28 forgenerating plasma in CVD apparatus 25.

Ar-gas cylinders 21a and 21b supply argon (Ar) gas, which is used as acarrier, to CVD apparatus 25 respectively via bubblers 22 and 23.

Bubbler 22 stores a metal chelate of alkaline earth oxide used as thesource and heats it. The metal chelate is transferred to CVD apparatus25 which it is evaporated by the argon gas blown on it through Ar-gascylinder 21a.

Bubbler 23 stores a cyclopentadienyl compound of alkaline earth oxideused as the source and heats it. The cyclopentadienyl compound istransferred to CVD apparatus 25 when it is evaporated by the argon gasblown on it through Ar-gas cylinder 21b.

Oxygen cylinder 24 supplies oxygen (O₂) used as a reaction gas to CVDapparatus 25.

(1) For thermal CVDs performed with the present CVD apparatus, glasssubstrate 27 is put on heating unit 26 with the dielectric glass layeron glass substrate 27 to be heated with a certain temperature (350 to400° C. See Table 1 “HEATING TEMPERATURE FOR GLASS SUBSTRATE”). At thesame time, the pressure in the reaction container is reduced by ventingapparatus 29 (by about several tens Torr).

Bubbler 22 or 23 is used to heat the metal chelate or cyclopentadienylcompound of alkaline earth oxide used as the source to a certaintemperature (See Table 1, “TEMPERATURE OF BUBBLER”). At the same time,Ar gas is sent to bubbler 22 or 23 through Ar-gas cylinder 21a or 21band oxygen is sent through cylinder 24.

The metal chelate or cyclopentadienyl compound reacts with oxygen in CVDapparatus 25 to form a protecting layer consisting of an alkaline earthoxide on the surface of glass substrate 27.

(2) For plasma enhanced CVDs performed with the present CVD apparatus,the procedure is almost the same as that of the thermal CVD describedabove. However, glass substrate 27 is heated by heating unit 26 withtemperature ranging from 250 to 300° C. (See Table 1, “HEATINGTEMPERATURE FOR GLASS SUBSTRATE”). At the same time, the pressure in thereaction container is reduced to about 10 Torr by venting apparatus 29.Under the circumstances, a protecting layer consisting of an alkalineearth oxide is formed by driving high-frequency power 28 to applyhigh-frequency electric field of 13.56 MHz, generating plasma in CVDapparatus 25.

Conventionally, the thermal CVD method or plasma enhanced CVD method hasnot been used for forming a protecting layer. One of the reasons for notusing these methods is that no appropriate source for these methods wasfound. The present inventors have made it possible to form a protectinglayer with the thermal CVD method or plasma enhanced CVD method by usingthe sources described below.

The source (metal chelate or cyclopentadienyl compound) supplied throughbubblers 22 and 23:

-   -   alkaline earth dipivaloylmethane compound M(C₁₁H₁₉O₂)₂,    -   alkaline earth acetylacetone compound M(C₅H₇O₂)₂,    -   alkaline earth trifluoroacetylacetone compound M(C₅H₅F₃O₂)₂, and    -   alkaline earth cyclopentadiene compound M(C₅H₅)₂, where “M”        represents an alkaline earth element.

In the present embodiment, the alkaline earth metal is magnesium.Therefore, the sources are as follows: magnesium dipivaloyl methaneMg(C₁₁H₁₉O₂)₂, magnesium acetylacetone Mg(C₅H₇O₂)₂, magnesiumtrifluoroacetylacetone Mg(C₅H₅F₃O₂)₂, and cyclopentadienyl magnesiumMg(C₅H₅)₂.

The protecting layer formed with the thermal CVD method or plasmaenhanced CVD method allows the crystals of the alkaline earth oxides togrow slowly to form a dense protecting layer consisting of an alkalineearth oxide with (100)-face orientation.

Effects of Protecting Layer of Magnesium Oxide with (100)-FaceOrientation

The conventional protecting layer of magnesium oxide formed by vacuumvapor deposition method (electron-beam evaporation method) has(111)-crystal-face orientation according to X-ray analysis (See No. 15in Table 2 and Nos. 67 and 69 in Table 4). Compared to this, theprotecting layer of a magnesium oxide with (100)-face orientation hasthe following characteristics and effects:

(1) the magnesium oxide with (100)-face orientation extends PDP lifesince it protects dielectrics glass layer due to its sputteringresistance owing to its density;

(2) the magnesium oxide with (100)-face orientation reduces drivingvoltage of PDP and improves panel brightness since it has a largeemission coefficient (γ value) of secondary electron;

(3) The magnesium oxide with (111)-face orientation tends to react withthe water content in the air to form hydroxides since it forms faceswith the highest surface energy among a variety of faces withorientation (see Surface Techniques, Vol. 41, No. 4, 1990, page 50 andJapanese Laid-Open Patent Application No. 5-342991). Accordingly,magnesium oxide with (111)-face orientation has a problem that theformed hydroxides decompose during a discharge and reduce the amount ofthe emission of secondary electron. On the other hand, the protectinglayer of a magnesium oxide with (100)-face orientation is to a largeextent immune to this problem.

(4) The magnesium oxide with (111)-face orientation has a heatresistance of up to 350° C. On the other hand, since the protectinglayer of a magnesium oxide with (100)-face orientation has a higher heatresistance, heat treatment is carried out at a temperature of about 450°C. when the front cover plate and the back plate are bonded.

(5) With the protecting layer of a magnesium oxide with (100)-faceorientation, aging after bonding of panels is comparatively short.

These characteristics and effects are especially noticeable in theprotecting layer of a magnesium oxide with (100)-face orientation formedwith the thermal CVD method or plasma enhanced CVD method.

Relation between Xe Amount, Charging Pressure, and Brightness

The panel brightness improves by setting the amount of Xe in thedischarge gas to 10% by volume or more and by setting the chargingpressure for the discharge gas to the range of 500 to 760 Torr. Thefollowing are considered to be the reasons.

(1) Increase in the Amount of Ultraviolet Light

Setting the amount of Xe in the discharge gas to 10% by volume or moreand setting the charging pressure for the discharge gas to the range of500 to 760 Torr increase the amount of Xe in the discharge space,raising the amount of ultraviolet light emitted.

(2) Improvement in Conversion Efficiency of Fluorescent Substance withShift of Ultraviolet Light to Longer Wavelength

Conventionally, Xe emitted ultraviolet light mainly at 147 nm (resonanceline of Xe molecule) since the amount of Xe in the discharge gas was setto 5% by volume or less and the charging pressure for the discharge gasto less than 500 Torr. However, by setting the amount of Xe in thedischarge gas to 10% by volume or more and by setting the chargingpressure for the discharge gas to the range of 500 to 760 Torr,ultraviolet light emission at 173 nm (molecular beam of Xe molecule),being a long wavelength, increases, improving the conversion efficiencyof fluorescent substance (see a material published by Plasma Study Groupin Electrical Engineers of Japan, May 9, 1995).

The above reason will be backed up by the following description.

FIG. 4 is a graph showing the change in relation between the wavelengthand amount of the ultraviolet light for each charging pressure, theultraviolet light being emitted from Xe in He-Xe gas used as a dischargegas in a PDP. This graph is introduced in O Plus E, No. 195, 1996, page99.

It is apparent from FIG. 4 that if charging pressure is low, Xe emitsultraviolet light mainly at 147 nm (resonance line of Xe molecule) andthat as the charging pressure increases, the ratio of ultraviolet lightemission at 173 mm increases.

FIGS. 5(a)-(c) show relation between excitation wavelength and relativeradiation efficiency for each color of fluorescent substance. This graphis included in O Plus E, No. 195, 1996, page 99. It is apparent fromthis drawing that the relative radiation efficiency is higher at 173 nmof wavelength than at 147 nm for every color of fluorescent substrate.

Relation between Discharge Gas Charging Pressure, Distance “d” betweenDischarge Electrodes, and Panel Driving Voltage

The amount of Xe in the discharge gas and the charging pressure for thedischarge gas are set to higher levels in the present embodiment.However, generally, this is considered to bring an inconvenience in thatthe PDP driving voltage increases since discharge start voltage “V_(f)”increases as the amount of Xe in the discharge gas or the chargingpressure increases (see Japanese Laid-Open Patent Application No.6-342631, column 2, pp 8-16 and 1996 Electrical Engineers of JapanNational Conference Symposium, S3-1, Plasma Display Discharge, March,1996).

However, such an inconvenience does not always occur. As is describedbelow, the driving voltage may be low even if the charging pressure isset to a high level if distance “d” between discharge electrodes is setto a comparatively small value.

As described in Electronic Display Device, Ohm Corp., 1984, pp 113-114,the discharge start voltage V_(f) may be represented as a function of Pmultiplied by d which is called the Paschen's Law.

FIG. 6 shows relation between charging pressure P of the discharge gasand discharge start voltage V_(f) for two values of distance d: d=0.1mm; and d=0.05 mm.

As shown in this graph, discharge start voltage V_(f) corresponding tocharging pressure P of the discharge gas is represented by a curveincluding a minimum.

Charging pressure P, being equal to the minimum, increases as ddecreases. The curve of graph “a” (d=0.1 mm) passes through the minimumat 300 Torr, the curve of graph “b” (d=0.05 mm) at 600 Torr.

It is apparent from the above description that an appropriate valuecorresponding to distance d between discharge electrodes should be setas the charging pressure in order to keep PDP driving voltage low.

Also, it is possible to say that if distance d between dischargeelectrodes is set to 0.1 mm or less (desirably to about 0.05 mm), PDPdriving voltage is kept low even if the charging pressure for thedischarge gas is set to the range of 500 to 760 Torr.

As is apparent from the above description, the PDP of the presentembodiment shows high panel brightness since the amount of Xe in thedischarge gas is set to 10% by volume or more and the charging pressurefor the discharge gas is set to the range of 500 to 760 Torr. Also, thedriving voltage of the PDP of the present embodiment is kept low sincedistance d between discharge electrodes is set to 0.1 mm or less.Furthermore, the PDP of the present embodiment has a long life since itincludes a protecting layer of a dense magnesium oxide with (100)-faceorientation which shows good effects in protection.

EXAMPLES 1-9

Table 1 shows PDP Examples 1-9 which were made according to the presentembodiment. The cell size of the PDP was set as follows: the height ofpartition walls 7 is 0.15 mm, the distance between partition walls 7(cell pitch) 0.15 mm, and distance d between discharge electrodes 12 is0.05 mm.

Dielectric glass layer 13, being lead glass, was formed by transferringa mixture of 75% by weight of lead oxide (PbO), 15% by weight of boronoxide (B₂O₃), 10% by weight of silicon oxide (SiO₂), and organic binder(made by dissolving 10% ethyl cellulose in α-terpineol) onto front glasssubstrate 11 with display electrodes 12 by screen printing and bakingthem for 10 minutes at 520° C. The thickness of dielectric glass layer13 was set to 20 μm.

The ratio of He to Xe in the discharge gas and the charging pressurewere set as shown in Table 1 except that the ratio of He in thedischarge gas was set to less than 10% by volume for Examples 7 and 9and that the charging pressure for the discharge gas was set to lessthan 500 Torr for Examples 7 and 8.

Regarding to the method of forming the protecting layer, the thermal CVDmethod was applied to Examples 1, 3, 5, and 7-9, and the plasma enhancedCVD method to Examples 2, 4, and 6. Also, magnesium dipivaloyl methaneMg(C₁₁H₁₉O₂)₂ was used as the source for Examples 1, 2, 7, 8, and 9,magnesium acetylacetone Mg(C₅H₇O₂)₂ for Examples 3 and 4, andcyclopentadienyl magnesium Mg(C₅H₅)₂ for Examples 5 and 6.

The temperature of bubblers 22 and 23 and the heating temperature ofglass substrate 27 were set as shown in Table 1.

For the thermal CVD method, Ar gas was provided for one minute with theflow rate of 11/min., oxygen for one minute with the flow rate of21/min. Also, the layer forming speed was adjusted to 1.0 μm/min.,bringing the thickness of magnesium oxide protecting layer to 1.0 μm.

For the plasma enhanced CVD method, Ar gas was provided for one minutewith the flow rate of 11/min., oxygen for one minute with the flow rateof 21/min. High-frequency wave was applied for one minute with 300W.Also, the layer forming speed was adjusted to 0.9 μm/min., bringing thethickness of magnesium oxide protecting layer to 0.9 μm.

With the X-ray analysis of the protecting layers of Examples 1-9, whichhad been formed as described above, it was confirmed for each Examplethat the crystals of magnesium oxides have (100)-face orientation.

Embodiment 2

The overall structure and production method of the PDP of the presentembodiment is the same as that of Embodiment 1 except that a denseprotecting layer consisting of magnesium oxide with (100)-faceorientation is formed with a printing method shown below.

Forming of Processing Layer with Printing Method

A dense protecting layer consisting of magnesium oxide with (100)-faceorientation is formed by transferring magnesium salt paste with aplate-shaped crystal structure onto the dielectric glass layer andbaking it.

The magnesium salts with a plate-shaped crystal structure for use aremagnesium carbonate (MgCO₃), magnesium hydroxide (Mg(OH)₂), magnesiumoxalate (MgC₂O₄), etc. The production methods of these magnesium saltsare described below in Examples 10-14.

The dense protecting layer consisting of magnesium oxide with (100)-faceorientation formed by the printing method has the same effects as thatformed with the method shown in Embodiment 1.

EXAMPLES 10-15

Table 2 shows PDP Examples 10-15 whose cell size and distance d betweendischarge electrodes 12 were set in the same way as PDP Examples 1-9.

Examples 10-14 were made according to the present embodiment. Example 15includes a protecting layer formed by a conventional vacuum vapordeposition method.

The magnesium oxalate (MgC₂O₄) with a plate-shaped crystal structureused for Example 10 was produbed by dissolving ammonium oxalate(NH₄HC₂O₄) in magnesium chloride (MgCl₂) aqueous solution to make amagnesium oxalate aqueous solution then heating it at 150° C.

The magnesium carbonate with a plate-shaped crystal structure used forExample 11 was produced by dissolving ammonium carbonate ((NH₄₎₂CO₃) inmagnesium chloride (MgCl₂) aqueous solution to make magnesium carbonate(MgCO₃), then heating it in carbonic acid gas to 900° C.

The magnesium hydroxide with a plate-shaped crystal structure used forExamples 12-14 was produced by dissolving sodium hydroxide (NaOH) in amagnesium chloride (MgCl₂) aqueous solution to make magnesium hydroxide(Mg(OH)₂), then pressurizing and heating it in sodium hydroxide at 5atmosphere pressures and 900° C.

Each of the magnesium salts with a plate-shaped crystal structure madeas described above was mixed with an organic binder (made by dissolving10% ethyl cellulose in 90% by weight of terpineol) by using athree-roller mill to establish a paste, then the paste was transferredonto the dielectrics glass layer by screen printing with a thickness of3.5 μm.

After baking each of these for 20 minutes at 500° C., a protecting layerconsisting of magnesium oxide with a thickness of about 1.7 μm wasformed.

With the X-ray analysis of the protecting layers of Examples 10-14,which had been formed as described above, it was confirmed for eachExample that the crystals of magnesium oxides had (100)-faceorientation.

For Example 15, a protecting layer was formed by the vacuum vapordeposition method, that is, by heating magnesium oxide with electronbeam. With the X-ray analysis of the protecting layer, it was confirmedthat the crystals of magnesium oxides had (111)-face orientation.

Embodiment 3

The overall structure and production method of the PDP of the presentembodiment is the same as that of Embodiment 1 except that a gasincluding Ar or Kr, namely Ar-Xe, Kr-Xe, Ar-Ne-Xe, Ar-He-Xe, Kr-Ne-Xe,or Kr-He-Xe gas is used as the discharge gas.

By mixing Ar or Kr with the discharge gas, the panel brightness isfurther improved. The reason is considered that the ratio of ultravioletlight emission at 173 nm increases further.

Here, it is desirable that the amount of Xe is set to the range from 10to 70% by volume since the driving voltage tends to rise if the amountexceeds 70% by volume.

Also, for three-element discharge gases such as Ar-Ne-Xe, Ar-He-Xe,Kr-Ne-Xe, and Kr-He-Xe gases, it is desirable that the amount of Kr, Ar,He, or Ne should be in the range of 10 to 50% by volume.

In the present embodiment, in forming a protecting layer, a method forevaporating a magnesium oxide with (110)-face orientation onto thedielectrics glass layer with irradiation of ion or electron beam is usedas well as the thermal CVD or plasma enhanced CVD method for formingmagnesium oxide with (100)-face orientation as described inEmbodiment 1. The method is described below.

Method for Evaporating Alkaline Earth Oxide onto Dielectrics Glass Layerby Use of Ion or Electron Beam Irradiation to Form Protecting Layer

FIG. 7 shows an ion/electron beam irradiating apparatus which is usedfor forming a protecting layer in the PDP of the present embodiment.

The ion/electron beam irradiating apparatus includes vacuum chamber 45to which glass substrate 41 with a dielectrics glass layer is attached.Vacuum chamber 45 also includes electron gun 42 for evaporating analkaline earth oxide (in the present embodiment, magnesium oxide).

Ion gun 43 irradiates ion beam to vapor of the alkaline earth oxidewhich has been evaporated by electron gun 42. Electron gun 44 irradiateselectron beam to vapor of the alkaline earth oxide evaporated byelectron gun 42.

The following description shows how to evaporate the alkaline earthoxide onto the dielectric glass layer by irradiating ion or electronbeam to vapor using the ion/electron beam irradiating apparatus of thepresent invention.

First, glass substrate 41 with a dielectric glass layer is set inchamber 45 then crystals of an alkaline earth oxide are put in electrongun 42.

Secondly, chamber 45 is evacuated then substrate 41 is heated (150° C.).Electron gun 42 is used to evaporate the alkaline earth oxide. At thesame time, ion gun 43 or electron gun 44 is used to irradiate argon ionor electron beam towards substrate 41. It forms a protecting layer of analkaline earth oxide.

The crystals of the alkaline earth oxide grow slowly and a denseprotecting layer consisting of an alkaline earth oxide with (110)-faceorientation is formed when, as is described above, the alkaline earthoxide is evaporated onto the dielectrics glass layer by irradiation ofthe ion or electron beam. The formed protecting layer shows almost thesame effects as the dense protecting layer of an alkaline earth oxidewith (100)-face orientation formed in Embodiment 1.

EXAMPLES 16-34

Table 3 shows PDP Examples 16-34 which were made according to thepresent embodiment. Refer to “DISCHARGE GAS TYPE AND RATIO” column inthe table for the discharge gas compositions, and “GAS CHARGINGPRESSURE” column for charging pressures.

The protecting layer of Examples 16 and 27 were formed as described inEmbodiment 1 using magnesium dipivaloyl methane Mg(C₁₁H₁₉O₂)₂ as thesource with the thermal CVD method, and Examples 17, 23, 24, 28, 32, and33 with the plasma enhanced CVD method.

For Examples 18, 21, 22, 25, 26, and 34, ion beam (current of 10 mA) wasirradiated, and for Examples 19, 20, 30, and 31, electron beam (10 mA),to evaporate a magnesium oxide onto the dielectric glass layer to form aprotecting layer with a layer thickness of 5000A.

With the X-ray analysis of the protecting layers which had been formedby evaporating magnesium oxides onto the dielectrics glass layer withirradiation of ion or electron beam, it was confirmed that the crystalsof the magnesium oxides had (110)-face orientation.

Embodiment 4

The overall structure and production method of the PDP of the presentembodiment is the same as that of Embodiment 1 except that the cellpitch is set to a larger value and the amount of Xe in a He-Xe gas usedas the discharge gas is set to less than 10% by volume. Note that thedistance between electrodes “d” is set to an equal or larger value.

In the present embodiment, alkaline earth oxides with (100)-faceorientation other than magnesium oxide (MgO) are formed as theprotecting layers, such as beryllium oxide (BeO), calcium oxide (CaO),strontium oxide (SrO), and barium oxide (BaO).

These protecting layers are formed by using appropriate sources forrespective alkaline earths with the thermal or plasma enhanced CVDmethod described in Embodiment 1.

The discharge electrodes formed on the front glass substrate includes atin oxide-antimony oxide or an indium oxide-tin oxide.

The protecting layer of beryllium oxide, calcium oxide, strontium oxide,or barium oxide with (100)-face orientation has almost the same effectsas the magnesium oxide with (100)-face orientation formed in Embodiment1.

EXAMPLES 35-66

Table 4 shows PDP Examples 35-66 which were made according to thepresent embodiment. The height of the partition walls was set to 0.2 mm,the distance between partition walls (cell pitch) 0.3 mm, and distance dbetween discharge electrodes 0.05 mm. The discharge gas was a He-Xemixture gas including 5% by volume of Xe, and the charging pressure wasset to 500 Torr.

The discharge electrodes, which are made with sputtering andphoto-lithography methods, consist of indium oxide (In₂O₃) including 10%by weight of tin oxide (SnO₂).

The protecting layers were made with the thermal or plasma enhanced CVDmethod from metal chelate or cyclopentadienyl compounds of the alkalineearth oxides shown in Table 4 “CVD SOURCE” column. The formed layerswere of magnesium oxide, beryllium oxide, calcium oxide, strontiumoxide, or barium oxide as shown in “ALKALINE EARTH OXIDE” column.

With the X-ray analysis of the protecting layers, it was confirmed thateach Example had (100)-face orientation.

Reference

Examples 67-69 shown in Table 4 were made in the same way as Examples35-66. However, the protecting layers of Examples 67-69 were formed withdifferent methods: for Example 67, the vacuum vapor deposition methodfor evaporating magnesium oxide onto the dielectric glass layer byheating magnesium oxide with an electron beam was used; for Example 68,the sputtering was performed on magnesium oxide as the target; and forExample 69, the screen printing was done with magnesium oxide paste.

With the X-ray analysis of the protecting layers, it was confirmed thatthe magnesium oxide protecting layers of Examples 67 and 69 had(111)-face orientation. It was also confirmed that magnesium oxideprotecting layer of Examples 68 had (100)-face orientation. However, theprotecting layer of Example 68 is not considered as dense since it wasformed with the sputtering.

Experiment 1 Measuring Ultraviolet Light Wavelength and Panel Brightness(Initial Value)

Experiment Method

For Examples 1-15, the ultraviolet light wavelength and panel brightness(initial value) were measured when they were operated on 150V ofdischarge maintenance voltage and 30 KHz of frequency.

Results and Analysis

As shown in Tables 1-3, resonance lines of Xe with a wavelength of 147nm were mainly observed from examples 7-9, showing low panel brightness(around 200 cd/m²), while molecular beams of Xe with a wavelength of 173nm were mainly observed from examples 1-6 and 10-34, showing high panelbrightness (around 400 cd/m² or more). Of these, Examples 16-34 showedthe highest panel brightness (around, 500 cd/m² or more).

It is apparent from the above results that the panel brightness isimproved by setting the amount of Xe in the discharge gas to 10% byvolume or more, charging pressure to 500 Torr or more and that the panelbrightness is further improved by mixing Kr or Ar with the dischargegas.

The panel brightness of example 15 is slightly lower than those ofExamples 1-6 and 10-14. The reason is considered to be that theprotecting layer of Example 15 consisting of magnesium oxide with(111)-face orientation emits less secondary electrons than that with(100)-face orientation.

Experiment 2 Measuring Change Rates of Panel Brightness and DischargeMaintenance Voltage

Experiment Method

For Examples 1-15 and 35-69, the change rates (change rates fromrespective initial values after 7,000 hours of operation) of panelbrightness and discharge maintenance voltage were measured after theywere operated for 7,000 hours on 150V of discharge maintenance voltageand 30 kHz of frequency.

For Examples 16-34, the change rates of panel brightness and dischargemaintenance voltage were measured after they were operated for 5,000hours on 170V of discharge maintenance voltage and 30 kHz of frequency.

Results and Analysis

As shown in Tables 1 and 2, the panel brightness change rates ofexamples 1-6 and 10-14 are smaller than those of examples 7-9. Also, asshown in Table 3, the change rates of panel brightness and dischargemaintenance voltage of examples 16-34 were small as a whole.

It is apparent from the above results that the panel brightness changerate reduces by setting the amount of Xe in discharge gas to 10% byvolume or more, charging pressure to 500 Torr or more.

The change rates of panel brightness and discharge maintenance voltageof examples 1-14 are smaller than those of Example 15. The reason isconsidered that the protecting layer of magnesium oxide with (111)-faceorientation has higher sputtering resistance and higher efficiency inprotecting dielectrics glass layer than that with (100)-faceorientation.

As shown in Table 4, the change rates of panel brightness and dischargemaintenance voltage of examples 35-66 are little, and those of examples67-69 great.

The above results show that generally the protecting layer of alkalineearth oxide with (100)-face or (110)-face orientation formed with thethermal CVD method, plasma enhanced CVD method, or vapor depositionmethod with ion or electron beam irradiation has higher sputteringresistance and higher efficiency in protecting dielectrics glass layerthan that with (111)-face orientation. Note that the results of example67 show that the protecting layer consisting of alkaline earth oxidewith (100)-face orientation formed with the sputtering method has highchange rates of panel brightness and discharge maintenance voltage andlow efficiency in protecting dielectrics glass layer.

The reason for the above results is considered that for the alkalineearth oxide of the protecting layer which has been formed by the thermalCVD, plasma enhanced CVD, or a method of evaporating the oxide onto alayer by irradiating ion or electron beam, the crystals grow slowly toform a dense protecting layer with (100)-face or (110)-face orientation;for the protecting layer formed by the sputtering method, the crystalsdo not grow slowly and the protecting layer does not become dense thoughit has (100)-face orientation.

Others

The values in Tables 1-4 in “BUBBLER TEMPERATURE,” “HEATING TEMPERATUREFOR GLASS SUBSTRATE,” “PANEL BAKING TEMPERATURE,” “PRINTED LAYERTHICKNESS,” “Ar GAS FLOW RATE,” and “O₂ GAS FLOW RATE” were consideredto be optimum for the respective alkaline earth sources.

The results of the change rates of panel brightness and dielectricmaintenance voltage shown in Table 4 were obtained from PDPs with 5% byvolume of Xe in discharge gas. However, the same results may be obtainedfrom those with 10% by volume or more of Xe.

In the above Embodiments, the back panel of the PDPs includes back glasssubstrate 15 with which partition walls 17 are bonded. However, thepresent invention is not limited to such construction and may be appliedto general AC PDPs such as those having partition walls attached to thefront panel.

Although the present invention has been fully described by way ofexamples with reference to the accompanying drawings, it is to be notedthat various changes and modifications will be apparent to those skilledin the art. Therefore, unless such changes and modifications depart fromthe scope of the present invention, they should be construed as beingincluded therein.

TABLE 1 PROTECTING HEATING DISCHARGE LAYER BUBBLER TEMPERATURE X-RAY GASTYPE EXAMPLE FORMING TEMPERATURE FOR GLASS ANALYSIS AND RATIO No. METHODCVD SOURCE (° C.) SUBSTRATE (° C.) RESULT (%) 1 THERMAL Mg(C₁₁H₁₉O₂)₂125 350 (100)-FACE He(90)-Xe(10) CVD ORIENTATION 2 PLASMA Mg(C₁₁H₁₉O₂)₂125 250 (100)-FACE He(80)-Xe(20) ENHANCED ORIENTATION CVD 3 THERMALMg(C₅H₇O)₂ 185 400 (100)-FACE He(50)-Xe(50) CVD ORIENTATION 4 PLASMA ″ ″300 (100)-FACE He(10)-Xe(90) ENHANCED ORIENTATION CVD 5 THERMALMg(C₅H₆)₂  80 350 (100)-FACE He(1)-Xe(99) CVD ORIENTATION 6 PLASMA ″  80250 (100)-FACE He(30)-Xe(70) CVD ORIENTATION 7 THERMAL Mg(C₁₁H₁₉O₂)₂ 125350 (100)-FACE He(98)-Xe(2) CVD ORIENTATION 8 THERMAL ″ ″ ″ (100)-FACEHe(80)-Xe(20) CVD ORIENTATION 9 THERMAL ″ ″ ″ (100)-FACE He(90)-Xe(5)CVD ORIENTATION CHARACTERISTICS CHANGE RATE AFTER GAS ULTRA PANEL 7000H, 150 V, 30 KHz CHARGING VIOLET BRIGHTNESS PANEL DISCHARGE EXAMPLEPRESSURE RAY (INITIAL VALUE) BRIGHTNESS MAINTENANCE No. (Torr)WAVELENGTH (cd/m²) (%) VOLTAGE (%) 1 500 173 nm BY 430 −8.4 2.4MOLECULAR BEAM 2 600 173 nm BY 450 −7.8 2.2 MOLECULAR BEAM 3 650 173 nmBY 460 −7.5 2.3 MOLECULAR BEAM 4 700 173 nm BY 440 −7.0 2.4 MOLECULARBEAM 5 650 173 nm BY 430 −7.2 2.3 MOLECULAR BEAM 6 760 173 nm BY 435−7.5 2.5 MOLECULAR BEAM 7 300 147 nm BY 205 −9.4 2.5 RESONANCE LINE 8450 147 nm BY 210 −9.5 2.8 RESONANCE LINE 9 550 147 nm BY 205 −9.8 2.9RESONANCE LINE

TABLE 2 GAINED PRINTED PANEL SOURCE OF PLATE-SHAPED LAYER BAKING X-RAYDISCHARGE GAS EXAMPLE PLATE-SHAPED MAGNESIUM THICKNESS TEMPERATUREANALYSIS TYPE AND RATIO No. MgO SALT (μm) (° C.) RESULT (%) 10MgCl2,NH4HC2O4 MgC2O4 3.5 500 (100)-FACE Ne(50)-Xe(50) ORIENTATION 11MgCl2,(NH4)2CO3 MgCO3 ″ ″ (100)-FACE Ne(30)-Xe(70) ORIENTATION 12MgCl2,NaOH Mg(OH)2 ″ ″ (100)-FACE Ne(60)-Xe(40) ORIENTATION 13 ″ ″ ″ ″(100)-FACE Ne(1)-Xe(99) ORIENTATION 14 ″ ″ ″ ″ (100)-FACE Ne(90)-Xe(10)ORIENTATION 15 VACUUM VAPOR DEPOSITION ON MgO WITH ELECTRON BEAM(111)-FACE Ne(50)-Xe(50) ORIENTATION CHARACTERISTICS GAS ULTRA PANELCHANGE RATE AFTER CHARGING VIOLET BRIGHTNESS PANEL DISCHARGE EXAMPLEPRESSURE RAY (INITIAL VALUE) BRIGHTNESS MAINTENANCE No. (Torr)WAVELENGTH (cd/m²) (%) VOLTAGE (%) 10 650 173 nm BY 410 −5.8 2.2MOLECULAR BEAM 11 700 173 nm BY 425 −6.5 2.8 MOLECULAR BEAM 12 550 173nm BY 430 −7.2 2.6 MOLECULAR BEAM 13 600 173 nm BY 415 −7.5 2.8MOLECULAR BEAM 14 760 173 nm BY 408 −7.2 2.9 MOLECULAR BEAM 15 650 173nm BY 380 −15.8 3.2 MOLECULAR BEAM

TABLE 3 HEATING PROTECTING TEMPERATURE DISCHARGE LAYER BUBBLER FOR GLASSX-RAY GAS TYPE EXAMPLE FORMING TEMPERATURE SUBSTRATE ANALYSIS AND RATIONo. METHOD CVD SOURCE (° C.) (° C.) RESULT (%) 16 THERMAL Mg(C₁₁H₁₉O₂)₂125 350 (100)-FACE Ar(90)-Xe(10) CVD ORIENTATION 17 PLASMA Mg(C₁₁H₁₉O₂)₂125 250 (100)-FACE Ar(50)-Xe(50) ENHANCED ORIENTATION CVD 18 VAPORDEPOSITION OF MgO BY IRRADIATING 150 (110)-FACE Ar(30)-Xe(70) ION BEAMORIENTATION 19 VAPOR DEPOSITION OF MgO BY IRRADIATING ″ (110)-FACE ″ELECTRON BEAM ORIENTATION 20 VAPOR DEPOSITION OF MgO BY IRRADIATING ″(110)-FACE Kr(90)-Xe(10) ELECTRON BEAM ORIENTATION 21 VAPOR DEPOSITIONOF MgO BY IRRADIATING ″ (110)-FACE Kr(50)-Xe(50) ION BEAM ORIENTATION 22VAPOR DEPOSITION OF MgO BY IRRADIATING ″ (110)-FACE Kr(30)-Xe(70) IONBEAM ORIENTATION 23 PLASMA Mg(C₁₁H₁₉O₂)₂ 125 250 (100)-FACEXe(10)-Ar(40)-Ne(50) ENHANCED ORIENTATION CVD 24 PLASMA ″ ″ ″ (100)-FACEXe(40)-Ar(50)-Ne(10) ENHANCED ORIENTATION CVD 25 VAPOR DEPOSITION OF MgOBY IRRADIATING 150 (110)-FACE Xe(70)-Ar(10)-Ne(20) ION BEAM ORIENTATION26 VAPOR DEPOSITION OF MgO BY IRRADIATING ″ (110)-FACEXe(10)-Ar(40)-Ne(50) ION BEAM 27 THERMAL Mg(C₁₁H₁₉O₂)₂ 125 350(100)-FACE Xe(40)-Ar(50)-Ne(10) CVD ORIENTATION 28 PLASMA ″ ″ 250(100)-FACE Xe(70)-Ar(10)-Ne(20) ENHANCED ORIENTATION CVD 29 PLASMA ″ ″ ″(100)-FACE Xe(10)-Ar(40)-Ne(50) ENHANCED ORIENTATION CVD 30 VAPORDEPOSITION OF MgO BY IRRADIATING 150 (110)-FACE Xe(40)-Ar(50)-Ne(10)ELECTRON BEAM ORIENTATION 31 VAPOR DEPOSITION OF MgO BY IRRADIATING ″(110)-FACE Xe(70)-Ar(10)-Ne(20) ELECTRON BEAM ORIENTATION 32 PLASMAMg(C₁₁H₁₉O₂)₂ 125 250 (100)-FACE Xe(10)-Ar(40)-Ne(50) ENHANCEDORIENTATION CVD 33 PLASMA Mg(C₁₁H₁₉O₂)₂ ″ ″ (100)-FACEXe(40)-Ar(50)-Ne(10) ENHANCED ORIENTATION CVD 34 VAPOR DEPOSITION OF MgOBY IRRADIATING 150 (110)-FACE Xe(70)-Ar(10)-Ne(20) ION BEAM ORIENTATIONCHARACTERISTICS CHANGE RATE AFTER GAS ULTRA- PANEL 7000 H, 150 V, 30 KHzCHARGING VIOLET BRIGHTNESS PANEL DISCHARGE EXAMPLE PRESSURE RAY (INITIALVALUE) BRIGHTNESS MAINTENANCE No. (Torr) WAVELENGTH (cd/m²) (%) VOLTAGE(%) 16 500 173 nm BY MOLECULAR 501 −6.5 2.0 BEAM 17 600 173 nm BYMOLECULAR 505 −5.2 1.9 BEAM 18 550 173 nm BY MOLECULAR 502 −5.8 2.1 BEAM19 ″ 173 nm BY MOLECULAR 498 −6.0 2.2 BEAM 20 650 173 nm BY MOLECULAR512 −6.2 2.5 BEAM 21 550 173 nm BY MOLECULAR 516 −7.1 2.2 BEAM 22 590173 nm BY MOLECULAR 513 −6.0 2.3 BEAM 23 760 173 nm BY MOLECULAR 495−4.2 2.4 BEAM 24 600 173 nm BY MOLECULAR 513 −5.8 2.1 BEAM 25 550 173 nmBY MOLECULAR 508 −5.9 2.3 BEAM 26 520 173 nm BY MOLECULAR 506 −5.2 2.627 580 173 nm BY MOLECULAR 518 −5.0 2.5 BEAM 28 610 173 nm BY MOLECULAR503 4.9 2.1 BEAM 29 650 173 nm BY MOLECULAR 521 4.5 2.4 BEAM 30 700 173nm BY MOLECULAR 510 −4.3 2.3 BEAM 31 630 173 nm BY MOLECULAR 508 −4.72.2 BEAM 32 500 173 nm BY MOLECULAR 518 −5.0 2.7 BEAM 33 750 173 nm BYMOLECULAR 511 −4.4 2.6 BEAM 34 590 173 nm BY MOLECULAR 506 −4.9 2.4 BEAM

TABLE 4 HEATING PROTECTING Ar GAS O₂ GAS X-RAY ANALYSIS BUBBLERTEMPERATURE LAYER FLOW FLOW RESULT EXAMPLE TEMPERATURE FOR GLASS FORMINGRATE RATE ALKALINE CRYSTAL No. CVD SOURCE (° C.) SUBSTRATE (° C.) METHOD(l/min.) (l/min.) EARTH OXIDE ORIENTATION 35 Mg(C₁₁H₁₉O₂)₂ 125 350THERMAL 1   2   MgO (100)-FACE CVD ORIENTATION 36 ″ ″ 250 PLASMA EN- ″ ″″ (100)-FACE HANCED CVD ORIENTATION 37 Be(C₁₁H₁₉O₂)₂ 110 350 THERMAL ″ ″BeO (100)-FACE CVD ORIENTATION 38 ″ ″ 250 PLASMA EN- ″ ″ ″ (100)-FACEHANCED CVD ORIENTATION 39 Ca(C₁₁H₁₉O₂)₂ 130 400 THERMAL ″ ″ CaO(100)-FACE CVD ORIENTATION 40 ″ ″ 300 PLASMA EN- ″ ″ ″ (100)-FACE HANCEDCVD ORIENTATION 41 Sr(C₁₁H₁₉O₂)₂ 135 400 THERMAL ″ ″ SrO (100)-FACE CVDORIENTATION 42 ″ ″ 300 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 43 Be(C₁₁H₁₉O₂)₂ 140 400 THERMAL ″ ″ BaO (100)-FACE CVDORIENTATION 44 ″ ″ 300 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 45 Mg(C₅H₇O)₂ 165 400 THERMAL 1.5 2.5 MgO (100)-FACE CVDORIENTATION 46 ″ ″ 300 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 47 Be(C₅H₇O)₂ 150 400 THERMAL 1.3 2.4 BeO (100)-FACE CVDORIENTATION 48 Ca(C₅H₇O)₂ 190 350 THERMAL 0.8 2.0 CaO (100)-FACE CVDORIENTATION 49 Sr(C₅H₇O)₂ 195 ″ THERMAL ″ ″ SrO (100)-FACE CVDORIENTATION 50 Ba(C₅H₇O)₂ 200 350 THERMAL 0.8 2   BaO (100)-FACE CVDORIENTATION 51 Mg(C₅H₅F₃O₂)₂ 115 450 THERMAL 0.5 1.5 MgO (100)-FACE CVDORIENTATION 52 ″ 115 350 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 53 Be(C₅H₅F₃O₂)₂ 100 450 THERMAL ″ ″ BeO (100)-FACE CVDORIENTATION 54 Ca(C₅H₅F₃O₂)₂ 120 ″ THERMAL ″ ″ CaO (100)-FACE CVDORIENTATION 55 Sr(C₅H₅F₃O₂)₂ 125 ″ THERMAL ″ ″ SrO (100)-FACE CVDORIENTATION 56 Ba(C₅H₅F₃O₂)₂ 130 ″ THERMAL ″ ″ BaO (100)-FACE CVDORIENTATION 57 Mg(C₂H₅)₂  80 350 THERMAL 1   2   MgO (100)-FACE CVDORIENTATION 58 ″ ″ 250 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 59 Be(C₂H₅)₂  75 350 THERMAL ″ ″ BeO (100)-FACE CVDORIENTATION 60 ″ ″ 250 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 61 Ca(C₂H₅)₂  90 350 THERMAL ″ ″ CaO (100)-FACE CVDORIENTATION 62 ″ ″ 250 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 63 Sr(C₂H₅)₂  95 350 THERMAL ″ ″ SrO (100)-FACE CVDORIENTATION 64 ″ ″ 250 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 65 Ba(C₂H₅)₂  98 350 THERMAL ″ ″ BaO (100)-FACE CVDORIENTATION 66 ″ ″ 250 PLASMA EN- ″ ″ ″ (100)-FACE HANCED CVDORIENTATION 67 VAPORATE MgO BY 350 VACUUM — — MgO (111)-FACE IRRADIATINGELECTRON BEAM VAPOR ORIENTATION DEPOSITION 68 SPUTTERING ON MgO ″SPUTTERING — — ″ (100)-FACE ORIENTATION 69 SCREEN PRINTING ON ″ SCREEN —— ″ (111)-FACE MgO PASTE PRINTING ORIENTATION CHARACTERISTICS ALKALINECHANGE RATE AFTER EARTH OXIDE 7000 H, 150 V, 30 KHz LAYER DEPOSITIONPANEL DISCHARGE EXAMPLE THICKNESS SPEED BRIGHTNESS MAINTENANCE No. (μm)(μm/min.) (%) VOLTAGE (%) 35 1.0 1.0 −9.5% 2.5% 36 0.9 0.9 −8.5% 2.3% 370.8 0.8 −10.2% 2.9% 38 0.7 0.7 −10.1% 3.0% 39 1.0 1.0 −9.4% 2.5% 40 0.90.9 −9.2% 2.4% 41 0.7 0.7 −9.3% 2.6% 42 0.6 0.6 −9.1% 2.5% 43 0.8 0.8−9.1% 2.7% 44 0.7 0.7 −9.0% 2.6% 45 0.6 0.6 −8.5% 2.5% 46 0.5 0.5 −8.3%2.4% 47 0.8 0.8 −8.5% 2.7% 48 0.7 0.7 −9.0% 2.6% 49 0.8 0.8 −9.2% 2.4%50 0.7 0.7 −9.5% 2.8% 51 0.7 0.7 −8.8% 2.3% 52 0.6 0.6 −8.5% 2.2% 53 0.80.8 −8.5% 2.5% 54 0.6 0.6 −8.2% 2.3% 55 0.5 0.5 −9.3% 2.8% 56 0.4 0.4−8.8% 2.2% 57 1.1 1.1 −7.5% 2.0% 58 0.9 0.9 −7.1% 2.0% 59 1.2 1.2 −7.0%2.1% 60 1.0 1.0 −6.9% 2.0% 61 0.9 0.9 −8.2% 2.6% 62 0.8 0.8 −8.3% 2.7%63 0.8 0.8 −8.9% 2.5% 64 0.7 0.7 −9.0% 2.8% 65 0.9 0.9 −8.0% 2.2% 66 0.70.7 −8.0% 2.1% 67 0.8 0.8 −15.2% 8.5% 68 0.5 0.5 −10.2% 6.5% 69 1.0 —−25.1% 10.8%

1. A method of producing a PDP, the method comprising: a first step offorming a front cover plate by forming a first electrode and adielectric glass layer on a front glass substrate then forming aprotecting layer of an alkaline earth oxide with one of (100)-faceorientation and (110)-face orientation on the dielectric glass layer;and a second step of forming a back plate by forming a second electrodeand a fluorescent substance layer on a back glass substrate then bondingthe front cover plate, on which the protecting layer has been formed,with the back plate, and charging a gas medium into a plurality ofdischarge spaces which are formed between the front cover plate and theback plate, the front cover plate and the back plate facing to eachother.
 2. The method of producing a PDP of claim 1, wherein in the firststep, the protecting layer is formed with one of a thermal ChemicalVapor Deposition method and a plasma Chemical Vapor Deposition method byusing an alkaline earth organometallic compound and oxygen.
 3. Themethod of producing a PDP of claim 2, wherein the alkaline earthorganometallic compound used in the first step is one of an alkalineearth metal chelate compound and an alkaline earth cyclopentadienylcompound.
 4. The method of producing a PDP of claim 3, wherein thealkaline earth organometallic compound used in the first step is one ofM(C₁₁H₁₉O₂)₂, M(C₅H₇O₂)₂, M(C₅H₅F₃O₂)₂, and M(C₅H₅)₂, wherein Mrepresents one of magnesium, beryllium, calcium, strontium, and barium.5. A method of producing a plasma display panel having a plurality ofdischarge space cells with a front substrate and a rear substrate andwalls separating each cell, each discharge space is addressable bydisplay electrodes to cause the cell to emit light comprising:depositing a protective layer of an alkaline earth oxide having one of a(100) crystal face orientation and a (110) crystal face orientationextending across a top surface of each cell; and charging each cell witha discharge gas.
 6. The plasma display panel method of claim 5 whereineach cell is pressurized to pressure of approximately 500 to 760 Torrs.7. The plasma display panel method of claim 6 wherein each cell ischarged with an xenon discharge gas between 10% by volume toapproximately 100% by volume.
 8. The plasma display panel method ofclaim 7 wherein one of argon, kryptor, helium and neon is mixed with thexenon.
 9. The plasma display panel method of claim 7 wherein one ofargon and krypton is mixed with the xenon in sufficient volume toprovide ultraviolet light emission at a wavelength of 173 nm.
 10. Theplasma display panel method of claim 7 wherein two additional dischargegases within the range of 10% to 50% by volume are mixed with the xenon.11. The plasma display panel method of claim 6 wherein a distancebetween adjacent display electrodes in the same plane is no greater than0.1 mm.
 12. The plasma display panel method of claim 5 wherein theprotective layer is selected from a group consisting of MgO, BeO, CaO,SrO and BaO.
 13. The plasma display panel method of claim 5 wherein theprotective layer is magnesium oxide with a crystal face orientationof(110).
 14. The plasma display panel method of claim 5, wherein thefirst substrate includes a dielectric glass layer and the dielectricglass layer is heated to a temperature between 350° C. to 400° C. duringthe depositing of the protective layer by a thermal chemical vapordeposition.
 15. The plasma display panel method of claim 5, wherein thefront substrate includes a dielectric glass layer and the dielectricglass layer is heated to a temperature between 250° C. to 300° C. duringthe depositing of the protective layer by a plasma enhanced chemicalvapor deposition.
 16. The plasma display panel method of claim 5,wherein the front substrate includes an upper glass plate and a lowerdielectric glass layer, and display electrodes are formed fromdepositing a conductive paste on the upper glass plate, the paste isthen baked to harden it and subsequently is sandwiched with the lowerdielectric glass layer.
 17. The plasma display panel method of claim 5,wherein the protective layer is deposited by transferring a paste of thealkaline earth oxide to the front substrate and baking it.
 18. Theplasma display panel method of claim 17, wherein the paste is amagnesium salt with a plate-shaped crystal structure.
 19. The plasmadisplay panel method of claim 18, wherein the paste is magnesium oxalateformed by dissolving ammonium oxalate in a magnesium chloride aqueoussolution and heating it to form the plate-shaped crystal structure. 20.The plasma display panel method of claim 5, wherein the depositing ofthe protective layer is made by evaporating the alkaline earth oxidewith an ion/electron beam in a vacuum.
 21. A method of producing aplasma display panel having a plurality of discharge space cells, eachdischarge space cell is addressable by display electrodes to cause thecells to emit light, comprising: depositing a protective layer of analkaline earth compound selected from the group consisting ofM(C₁₁H₁₉O₂)₂, M(C₅H₇O₂)₂, M(C₅H₅F₃O₂)₂, and M(C₅H₅)₂, wherein Mrepresents one of magnesium, beryllium, calcium, strontium, and barium,the protective layer having one of a (100) crystal-face orientation anda (110) crystal-face orientation extending across a surface of eachcell; and charging each cell with a discharge gas.
 22. The plasmadisplay method of claim 21, wherein the protective layer is deposited byone of a thermal chemical vapor deposition step and a plasma enhancedchemical vapor deposition step.
 23. The plasma display method of claim22, wherein the discharge gas includes at least 10% by volume Xe and isat a pressure of at least 500 Torr.
 24. The plasma display method ofclaim 23, wherein the discharge gas includes one of Ar and Kr.
 25. Theplasma display method of claim 23 wherein the discharge gas is selectedfrom a group consisting of Ar-He-Xe, Ar-He-Xe, Kr-Ne-Xe, and Kr-He-Xeand the amount of Kr, Ar, He, or Ne should be in the range of 10% to 50%by volume.
 26. The plasma display method of claim 23, wherein thealkaline earth compound is selected from the croup consisting ofmagnesium dipivaloyl methane, magnesium acetylacetone, magnesiumtrifluoroacetylacetone, and cyclopentadienyl.
 27. A method of producinga plasma display panel having a plurality of discharge space cells, eachdischarge space cell is addressable by display electrodes to cause thecell to emit light, comprising: depositing a protective layer selectedfrom the group consisting of magnesium dipivaloyl methane, magnesiumacetylacetone, magnesium trifluoroacetylacetone, and cyclopentadienylmagnesium across a surface of each cell to provide one of a (100)crystal-face orientation and a (110) crystal-face orientation; andcharging each cell with a discharge gas including at least 10% by volumeXe at a pressure of at least 500 Torr.
 28. A system for forming aprotective layer on a plasma display panel comprising: a vacuum chamberhousing, means for supporting a plasma display panel substrate withelectrodes in the housing; means for heating the plasma display panelsubstrate; means for evaporating, from a source of magnesium oxide, apredetermined amount of magnesium oxide to provide the protective layeron the plasma display panel substrate; and an electron gun aligned withthe means for supporting for evaporating magnesium oxide, as applied tothe plasma display panel substrate, to provide a single layer of a ( 110)-face orientation of sufficient thickness to provide sputteringresistance during a predetermined life term of the plasma display panel.29. The system of claim 28 wherein the plasma display panel substrate isheated to a temperature of 150° C. and the magnesium oxide is applied toa thickness of 5000 A ° for the protective layer.